Foot and/or ankle problems following limb alignment changes in uni-compartmental knee arthroplasty

Abstract

Objective Foot and/or ankle (F/A) problems may be encountered in medial uni-compartmental knee (UKA) patients postoperatively due to the limb alignment changes and alterations in weight bearing of F/A. This study aimed to evaluate the risk factors and the incidence of foot and ankle (F/A) problems in (UKA) arthroplasty patients. Methods Patients who underwent UKA between 2016 and 2019 in our clinic were evaluated and the presence of F/A problems was recorded. Radiologic evaluations included hip knee ankle angle (HKA), medial proximal tibial angle, posterior tibial slope angle, talar tilt angle, talar inclination, talar dome to mechanical axis (TDMA), and talocrural angle (TCA) measured on preoperative and follow-up long-leg standing radiographs. The range of motion, Q angles, and muscle strengths were measured. Visual analog scale, physical performance limitations, and patient-reported activity limitations were evaluated for all patients. Patients with reported F/A problems were additionally evaluated with Foot Functional Index. Results Forty-four patients (38 female, 6 male; mean age 58.66 ± 8.6 years; mean BMI 31.30 ± 3.81, mean follow-up period 34.22 ± 18.95 months) were included in the study. There were 13 patients (29.5%) with reported F/A problems. Postoperative comparison of patients with and without F/A problems showed statistically significant differences in only WOMAC and SF12 physical health sub-scores ( p = 0.002, p = 0.003, respectively). There was no significant postoperative change in TDMA in patients with F/A problems ( p > 0.05) in contrast to patients without F/A problems ( p = 0.006). There was no statistically significant difference in preoperative TCA measurements between groups ( p = 0.79). Comparison of knee and ankle radiologic measurements between groups demonstrated significant difference only in postoperative HKA measurements (−2.82 ± 2.53 vs. −0.80 ± 3.12, p = 0.033). Conclusion F/A problems adversely affecting the functional status were frequent in our cohort of UKA patients. Postoperative residual varus deformity may be a risk factor for this. Therefore, if slight varus alignment is aimed at UKA patients, preoperative F/A status should be evaluated.